I recently got a new PC with an AC 7260 card in it.
I have it set up in the next room away from the router (Airport extreme 2015), and have ensured that the drivers are up to date (The ProSet is 18.40.4 while the driver says 220.127.116.11)
Running a speedtest.net test on the PC shows a max of about 47Mbps down, while running the same test on my 2016 Macbook gets 106Mbps down, both on the same 5ghz network (which has no interference when checked).
If the Intel® Dual Band Wireless-AC 7260 came installed by factory, Intel recommends to use the drivers provided by the computer manufacturer even if their latest version differs from that found in our download center. For your convenience, through this link: http://www.intel.com/content/www/us/en/support/topics/OEMs.html Computer Manufacturer Support Websites - you may find the contact information for your computer manufacturer.
These online solutions may help you improve your experience:
http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000005493.html Quick Checks to Improve or Fix Wireless Connection Issue.
http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000005544.html Recommended Settings for 802.11n Connectivity
http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000006042.html Improve your 802.11n Wireless Performance
http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000006697.html Data Rate Won't exceed 54 Mbps When WEP ot TKIP Encryption is Configured
Additionally, you can do the following:
1. Check Firewall and Antivirus settings as this may impact the speed.
2. Disable Bluetooth* if not necessary as Bluetooth* and WiFi share the same antennas.
3. Disable Power Saving Functions: Go to Control Panel >> Hardware and Sound >> Power Options >> Set it to High Performance and apply to default settings.
4. Check the Change Plan Settings >> Change Advanced Power Setting >> Wireless Adapter Settings >> Power Saving Mode and make sure both On Battery and Plugged In are set to maximum performance.
5. Go to Device Manager >> Network Adapters >> Intel® Dual Band Wireless-AC 7260, right click on it and select Properties.
6. Once you're there, select the tab that says Advanced and locate U-APSD Support and set it to Disabled.
7. Also, set Transmit Power to 5. Highest.
8. Set the Wireless Mode to 802.11 a/b/g and choose the wireless mode according to that of the support mode of your router.
9. Set the Preferred Band to Prefer 2.4GHz band.
10. Set the HT Mode to HT Mode
11. Set the 802.11n Channel Width for 2.4 GHz to limit 20MHz.
12. Set the Roaming Agressiveness to Lowest.
13. Set the Ad Hoc QoS Mode to WMM Disabled.
Let us know if these tips helped you.